Matheson's sister was one of the last people to ever see him at the university.

The siblings were going to school together, taking science classes and living in residence. When she didn't hear from Matheson for a couple of days, she left a note at his dorm.

At the time, police launched an investigation into his disappearance, area residents and students joined in the search and missing posters were circulated.

Matheson's mother doesn't think she will ever see her son alive again, but she still wants answers.

"I want to know what happened," says MacDonald. "I'd love to find his body, his remains."

The family has waited for two decades to have Matheson's name added to the major unsolved crimes rewards program. They hope the $150,000 reward is enough to motivate those who have information to come forward.

"With 20 years passing, this reward program may be the incentive needed to generate information," says RCMP Cpl. Scott MacRae.

The family is urging people who attended Acadia University in the 1990s to think back. They hope even a small clue may be the break they need to solve their son's mysterious disappearance.